For desktop and notebook computers, it becomes more and more important to manage power source. The more working load of a CPU has, the more electricity consumption it takes, i.e. the working load of the CPU is proportional to the electricity consumption. Therefore, the so-called environmental protection computer was developed and are available in the market. In the operation of the environmental protection computer, if for a period of time a user does not input a command, the computer enters an idle state automatically in order to save electrical power. No matter whether the environmental protection computer is in idle state or in operation state, the user cannot know the present working load of the CPU from the outside of the computer, thus, the optimum state of the CPU cannot be monitored and controlled.